Mylar filter blocks most of the visible light spectra (up to 99.9%) in difference to an H-alpha (see my previous blog entry). If you want to manage observing sun spots cost efficiently and cheap then Mylar filter would do the job for you. Although an H-alpha filter would provide you with more details such as solar prominences, the Mylar filter is just allowing you to watch the sun’s cromosphere and there fore just sunspots. However, since this filter is lightweighted, can be carried easily around and can be mounted on ordinary camera lenses that would allow you to witness a Venus/Mercurius passages or a solar eclipse if you want to travel somewhere without carrying around heavy telescope equipment.
I personally prefer Baader’s astrosolar filter due to good quality. A Mylar filter must be kept dry and in room temperature if you want it to be long lived. It is nessesary to inspect your filter before attaching it on your telescope/camera lens since even a small pinhole can damage your eyes permanently during observation, without even noticing!
The best way to inspect your filter before using it, is by placing it infront of a flash light in a dark room. That way you would easily be able to spot any damage on it’s surface.
To photograph the sun doesn’t only require you to have the right settings on your camera, but you have to take multiple shots in order to get a clear shot spared from atmospherical distortions which are more intense and common during daytime. Most astrophotographers are using explicitly a web camera to shoot planetary objects, allowing them to get rid of unwanted images by running the video sequence through a software such as Registax. I’ve got a Youtube video showing you how these atmospherical distortions look like, by clicking here (Beware of the sound).
The image above shows the sun spots 1161 and 1162 as they appeared on Sunday 21 February 2011. Canon EOS 50D, ISO 250, Shutter speed 1/8000, WB: Custom, William Optics Megrez 72 Doublet APO, Image was processed in Adobe PS.